Electronic paper is getting more and more attention for its advantageous such as extremely low power consumption and suitability for human reading. Nowadays, electrophoretic electronic paper has two display types, namely microcapsule and micro-cup. The display principle of the electronic paper is that electrophoresis liquid encapsulated in the microcapsules or micro-cups comprises black electrophoretic particles negatively charged and white electrophoretic particles positively charged. As shown in FIG. 1, if an upper substrate is positively charged and a bottom substrate is negatively charged, the black electrophoretic particles 3 that are negatively charged move upwards while the white electrophoretic particles 4 that are positively charged move downwards due to the principle that same electric charges mutually repel and opposite electric charges mutually attract, thus corresponding micro-structures present black. The electrophoretic display device displays images through contrast between black and white.
Current electronic paper displaying images is achieved through black electrophoretic particles absorbing and white electrophoretic particles reflecting natural light. So, the electronic paper only works in bright environments and cannot work in a dark environment.